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Durham University

Department of Biosciences

Profile

Publication details for Prof. Ehmke Pohl

Chisholm, DR, Tomlinson, CWE, Zhou, G-L, Holden, C, Affleck, V Lamb, R, Newling, K, Ashton, P, Valentine, R, Redfern, C, Erostyak, J, Makkai, G, Ambler, CA, Whiting, A & Pohl, E (2019). Fluorescent retinoic acid analogues as probes for biochemical and intracellular characterization of retinoid signalling pathways. ACS Chemical Biology 14(3): 369-377.

Author(s) from Durham

Abstract

Retinoids, such as all-trans-retinoic acid (ATRA), are endogenous signalling molecules derived from Vitamin A that influ-ence a variety of cellular processes through mediation of transcription events in the cell nucleus. Due to these wide-ranging and powerful biological activities, retinoids have emerged as therapeutic candidates of enormous potential. However, their use has been limited, to date, due to a lack of understanding of the complex and intricate signaling pathways that they con-trol. We have designed and synthesized a family of synthetic retinoids that exhibit strong, intrinsic, solvatochromatic fluo-rescence as multifunctional tools to interrogate these important biological activities. We utilized the unique photophysical characteristics of these fluorescent retinoids to develop a novel in vitro fluorometric binding assay to characterize and quanti-fy their binding to their cellular targets, including Cellular Retinoid Binding Protein II (CRABPII). The dihydroquinoline retinoid, DC360, exhibited particularly strong binding (Kd = 34.0 ± 2.5 nM) and we further used X-ray crystallography to solve the structure of the DC360-CRABPII complex to 1.8 Å, which showed that DC360 occupies the known hydrophobic retinoid-binding pocket. Finally, we used confocal fluorescence microscopy to image the cellular behaviour of the com-pounds in cultured human epithelial cells, highlighting a fascinating nuclear localisation, and used RNA sequencing to con-firm that the compounds regulate similar cellular processes to ATRA. We anticipate that the unique properties of these fluo-rescent retinoids can now be used to shed new light on the vital and highly complex retinoid signalling pathway.